docs: def node_display(root, expandattrs=False, expandvals=False, output=sys.stdout):
      """
      Write an indented representation of the Node object on the output;
      this is intended for testing/debugging purposes.
  
      :param root: a Node object
      :param bool expandattrs: if True, the values of the attributes are
                               also printed, not only the names
      :param bool expandvals: if True, the values of the tags are also printed,
                              not only the names.
      :param output: stream where to write the string representation of the node
      """
      _display(root, '', expandattrs, expandvals, output)